Fig. 4

Preoperative CT scan showing right upper lobe squamous carcinoma (a, arrowhead). Multiplanar sagittal reconstruction shows enlarged azygos vein (b, asterisk) coursing through the diaphragm and draining into the superior vena cava (b, arrowhead); the hepatic inferior vena cava cannot be visualized along its normal course (b, dashed line). Findings are consistent with agenesis of the hepatic inferior vena cava and azygos continuation